As catalysts to be used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein, isobutyraldehyde, isobutyric acid, or the like, it is known that those having a structure of a hetero polyacid and/or a salt thereof are effective, and there are a large number of proposals regarding compositions, physical properties, and production processes thereof.
These catalysts are usually produced by steps of preparation of a raw material mixed solution, drying, molding, baking, and the like. With regard to the production of the catalysts stably exhibiting high performance, there are a large number of reports on molding methods and baking methods.
For example, in Patent Document 1, a process for molding with mixing heat-resistant fibers has been proposed for the purpose of enhancing the strength of the catalysts. Moreover, in Patent Document 2, in the production of a hetero polyacid salt-based catalyst, there has been proposed a process of treating a molded catalyst under a certain humidity atmosphere and subsequently performing baking.